System of current-supply buses in aluminum-producing electrolyzers

ABSTRACT

A system of current-supply buses in aluminum-producing electrolyzers located at the beginning and at the end of a group of electrolyzers arranged lengthwise in a row, incorporates stacks of cathode buses located at the left and at the right with respect to a longitudinal axis of the row of electrolyzers along the direction of the current flow through the electrolyzers. The system includes at least two rows of series-connected electrolyzers, and according to the invention, the left and the right cathode stacks in each of the electrolyzers located at the end of the row at the current outlet, include portions running along the transverse wall of the electrolyzers towards the longitudinal axis thereof and continuing portions running along said axis, whereas the left cathode stack at the current inlet into the electrolyzers located at the beginning of each row, is arranged symmetrically with the left cathode stack at the current outlet from the electrolyzer located at the end of the row.

United States Patent [1 1 Nikiforov et al.

SYSTEM OF CURRENT-SUPPLY BUSES IN ALUMINUM-PRODUCING ELECTROLYZERS Inventors: Vladimir Pavlovich Nikiforov,

Moskovsky prospekt, 205, kv. 432; Nikolai Pavlovich Budkevich, Belgradskaya ulitsa, 38, korpus 5, kv. 40; Semen Emilievich Gefter, ulitsa Chaikovskogo, l8, kv. 6; Svetozar Vladimirovich Evdokimov, Lesnoi prospekt, 13/8, kv. 5; Ilya Genrikhovich Kil, Gavanskaya ulitsa, 37, kv. 61; Valentin IgnatievichRyabov, prospekt Nauki, l2, kv. 208; Alexandr Nikolaevich Smorodinov, Bukharestskaya ulitsa,

31, korpus 3, kv. 55; Igo Kirillovich Tsybukov, Tikhoretsky prospekt, 9, korpus 10, kv. 54; Anatoly .Mikhailovich Tsyplakov, prospekt Kima, 30, kv. 74, all of Leningrad, U.S .S.R.

Filed: Aug. 17, 197i Appl. Nor-172,422

Foreign Application Priority Data Nov. 27, 1973 Primary Examiner-John H. Mack Assistant Examiner-D. R. Valentine Attorney-Holman & Stern [5 7 ABSTRACT A system of current-supply buses in aluminum-' producing electrolyzers located at the beginning and at the end of a group of electrolyzers arranged lengthwise in a row, incorporates stacks of cathode buses'located at the left and at the right with respect to a longitudinal axis of the row of electrolyzers along the direction of the current flow through the electrolyzers. The system includes at least two rows of seriesconnected electrolyzers, and according to the invention, the left and the right cathode stacks in each of the electrolyzers located at the end of the row at the current outlet, include portions running along the transverse wall of the electrolyzers towards the longitudinal axis thereof and continuing portions running along said axis, whereas the left cathode stack at the current inlet into the electrolyzers located at the beginning of each row, is arranged symmetrically with the left cathode stack at the current outlet from the electrolyzer located at the end of the row.

2 Claims, 1 Drawing Figure BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to systems of current-supply buses in aluminium-producing electrolyzers located at the beginning and at the end of a row of electrolyzers which are arranged lengthwise in the row.

2.Description of Prior Art Known in the present state of the electrochemistry practice is a system of current-supply buses in aluminium-producing electrolyzers located at the beginning and at the end of a row of electrolyzers arranged lengthwise in the row, incorporating stacks of cathode buses arranged at the left and at the right with respect to the longitudinal axis of the electrolyzers in the direction of the current flow.

In the course of operation of electrolyzers provided in the known system of current-supply buses, powerful electromagnetic fields arise due to heavy currents passing through the electrolyzer elements which substantially influence the process of aluminium electrolysis and the economical characteristics thereof.

With increased power of an aluminium-producing electrolyzer, adverse effect of said magnetic field upon the aluminium'electrolysis is increased accordingly. In-

teraction of the magnetic field with the currents flowing through the molten metal in the electrolyzer causes a large-magnitude electromagnetic forces in the latter. These forces give rise to a distorted surface ofthe liquid cathode metal and to its vigorous circulation which is undesirable.

Considerable warping or buckling of the metal surface causes electrolyzers to operate at an electrode spacing appreciably exceeding the optimum one. This leads to an increase in the heating voltage, overexpenditure of electric power and over-heated melt which adversely tells on the current yield.

As a result of vigorous circulation the molten metal is much more liable to entrainment into the near-theanode space where it gets oxidized by anode gases. Numerous observations have shown that it is evident that in those zones of the electrolyzer bath wherein the magnetic field intensity and the level of circulating fluxes reaches their peak values, the side wall reinforcement of the electrolyzer becomes badly affected and it is in these zones that the side walls of electrolyzers are most frequently broken down and destroyed by the molten metal.

Furthermore, under the combined effect of gaseous fluxes and electromagnetic forces, waves arise on the surface of the fused aluminium which may result in local shorts that substantially reduce the current yield.

The exploitation and utilization of high-power electrolyzers may be economically warranted only if effective measures are developed to counteract the harmful effect of the magnetic field Investigations of the magnetic fields carried out during the recent years both on mocked-up and on industrial electrolyzers using heavy current, have made it possible to visualise the requirements of the system of current-supply buses of an aluminium-producing electrolyzer, as may be expressed in the following formula:

By O; (8 By/6 x) (8 Bx/8 y) 0; (6 82/6 x) 6 82/8 y 0; where:

By stands for the cross component of magnetic field; Bx denotes the longitudinal component of magnetic field;

Bz denotes the vertical component of magnetic field.

In other words, the afore-specified requirements imply the symmetry of the cross magnetic field, invariability of the values By and Bx along the axes of an electrolyzer and the requirement of a maximum possible diminishing of the absolute values of B2 effective at the electrolyzer corners, as well as the symmetry of the vertical magnetic field with respect to the electrolyzer axes.

There was proposed a bilateral asymmetrical system of current-supply buses for aluminium-producingelectrolyzers (cf. French patent No. l,586,867) made with due allowance for the influence exerted by the currentconducting elements of both the preceding and the following electrolyzers located in the same row, as well as for that of the electrolyzers of the adjacent row.

However, it must be noted that the-electrolyzers'located at the beginning and at the end of each row operate under other conditions different from those located in the middle of the row.

A characteristic feature of said end electrolyzers resides in the fact that they neighbour upon the adjacent electrolyzers on one side only. Besides, magnetic field established by the currents flowing along the opposite row of electrolyzers (with the. double-row arrangement of electrolyzers in a production room) is in this case somewhat lower.

Therefore, magnetic field effective in the liquid metal of the electrolyzers located at the beginning and at the end of a row (in particular, the vertical component of the field), when the known system of current-supply buses is employed without any additional measures taken, gets unsymmetrical which, in turn, exerts a pronounced influence upon the working characteristics of said electrolyzers which is evidenced by the production experience.

SUMMARY OF THE INVENTION It is an essential object of the present invention to eliminate the disadvantages mentioned above.

The present invention is directed to the development of a system of current-supply buses for aluminiumproducing electrolyzers located at the beginning and at the end of a row of electrolyzers arranged lengthwise; the system which features such. a position of the cathode buses with respect to the electrolyzer longitudinal axis that ensures the symmetry of the magnetic field and conduces to ensure higher production efficiency of the electrolyzer.

Said and other objects have been accomplished due to the provision of a system of current-supply buses for aluminium-producing electrolyzers'located at the'beginning and at the end of a row when said electrolyzers are arranged lengthwise in the row, incorporating stacks of cathode buses arranged at the left and at the right with respect to the electrolyzer longitudinal axis along the direction of current flow, wherein according to the invention the left-hand L.I-l. and the right-hand RH. cathode stacks in each of the electrolyzers located at the end of the row at the current outlet, run lengthwise of the transverse wall of the electrolyzer towards the longitudinal axis thereof and, further, lengthwise of said axis, whereas the LE. stack at the current inlet into the electrolyzer located at the beginning of each row, is arranged symmetrically with the L.I-I. stack located at the current outlet from the electrolyzer located at the end of the row.

Such an embodiment of the current-carrying buses of the electrolyzer provides for a higher current yield, this being due to the establishing of a symmetrical magnetic field, mostly along the vertical component thereof.

It is expedient that the L.I-I. and the RH. cathode stacks of the system of buses in each electrolyzer located at the end of the row at the current outlet, as well as the L.I-I. and the RH. cathode stacks at the current inlet into the electrolyzer at the beginning of the row be positioned at the same level.

In doing so use may be made of constructionally simpler supports for holding the buses.

BRIEF DESCRIPTION OF THE DRAWING To make the invention more evident given below is an exemplary embodiment of a system of currentsupply buses for electrolyzers set forth with due reference to the accompanying drawing illustrating a diagram of current-supply buses of electrolyzers, according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Now referring to the drawing the system of currentsupply buses for electrolyzers 1 and 2 producing aluminium and located at the beginning and at the end of the row, respectively is shown, both electrolyzers being arranged lengthwise in the row, said system incorporating stacks 3, 4 and 5, 6 of cathode buses arranged at the left and at the right with respect to the longitudinal axis of the electrolyzers along the current flow. According to the invention, the L.I-l. stack 3 and the R.I-I. stack 4 of cathode buses in each electrolyzer 2 located at the end of the row at the current outlet, run lengthwise in the direction of the electrolyzer transverse wall towards the longitudinal axis thereof and, further, lengthwise said wall, whereas the LB. stack 5 at the current inlet into the electrolyzer 1 located at the beginning of each row, is arranged symmetrically with the L.I-I. stack 3 at the current outlet from the electrolyzer 2 located at the end of the row.

In one of the embodiments of the system of currentsupply buses the I...H. stack 3 and the RH. stack 4 of cathode buses in each electrolyzer 2 located at the end of the row at the current outlet, and the L.H. stack 5 and the RH. stack 6 of cathode buses at the current inlet into the electrolyzer 1 located at the beginning of the row may be located at the same level.

Current supply of aluminium-producing electrolyzers by way of the system of buses as disclosed in the present invention, occurs as follows.

In a production room the electrolyzers are arranged in two rows which are spaced from each other. The system of current-supply buses of the electrolyzers 1' and 2' which are located at the ends of the first row is similar to that of the electrolyzers l and 2 located extremely in the second row, therefore the description given below refers only to only one set of electrolyzers i.e., electrolyzers l and 2.

The direction of the current flow in the stacks of cathode buses of the electrolyzers is indicated by arrows.

Current is taken from the cathode of the electrolyzer 2 by means of the L.H. stack 3 and the RH. stack 4 of cathode buses, while to the anode of the electrolyzer 1 current is fed via the stacks 5 and 6.

Each of the stacks 3 and 4 has sections located downstream the electrolyzer 2 at the current outlet therefrom and running in the direction of the transverse wall thereof, whereas upstream the electrolyzer 1 at the current inlet therein only the stack 5 has such a section.

As a result of such an arrangement of the cathode stacks 3, 4 and 5 at the beginning and at the end of the row, the magnetic field produced by the currents passing along these stacks, is effective to counteract the asymmetry of the vertical component 82 in the molten metal of the electrolyzer to which pertains the aforesaid stacks.

Equalization of the magnetic field of the electrolyzer 1 located at the beginning of the row due to a varied position of the stack 5 and equalization of the magnetic field of the electrolyzer 2 located at the end of the row clue to a varied position of the stacks 3 and 4 are attributed to the fact that the electrolyzer 1 at the current inlet and the electrolyzer 2 at the current outlet are provided respectively with risers 9, 10 and 7, 8 through the horizontal portion of which currents of different magnitudes are passing, as well as due to the provision of a busduct 11 running from one row of electrolyzers to the other.

The division of the magnitudes of current as a percentage of the total current magnitude as falling within the risers, may range in the following limits riser 7 0 to 15 percent,

riser 8 15 to 20 percent,

riser 9 30 to 35 percent,

riser l0 35 to 50 percent.

By varying both the position of the cathode stacks 3, 4 and 5 running in the direction of the transverse wall of the electrolyzer for height and their distance therefrom, one can attain an optimum distribution of the vertical component of the magnetic field over the molten metal of the electrolyzers located extremities of the row.

What we claim is z 1. A system of current-supply buses in aluminumproducing electrolyzers having transverse walls and located at the beginning and at the end of a plurality of series-econnected electrolyzers arranged in at least two rows along spaced longitudinal axes, said system comprising: left and right stacks of cathode buses located at the left and at the right with respect to each of said longitudinal axes of said electrolyzers viewing in the direction of current flow through the electrolyzers, said left and right stacks in each of said electrolyzers located at the end of each said row at the current outlet including portions which run lengthwise of the transverse wall of said electrolyzer towards the longitudinal axis thereof and continuing portions running lengthwise of the corresponding longitudinal axis, whereas the left stack of current supply bus at the current inlet into said electrolyzer located at the beginning of each row has a configuration symmetrical with said left stack located at the current outlet from said electrolyzer located at the end of the row.

2. A system of current-supply buses as claimed in claim 1, wherein said left and said right cathode stacks in each of said electrolyzers located at the end of the row at the current outlet and said left and said right cathode stacks at the current inlet into said electrolyzer located at the beginning of the row, are arranged at the same level. 

1. A system of current-supply buses in aluminum-producing electrolyzers having transverse walls and located at the beginning and at the end of a plurality of series-econnected electrolyzers arranged in at least two rows along spaced longitudinal axes, said system comprising: left and right stacks of cathode buses located at the left and at the right with respect to each of said longitudinal axes of said electrolyzers viewing in the direction of current flow through the electrolyzers, said left and right stacks in each of said electrolyzers located at the end of each said row at the current outlet including portions which run lengthwise of the transverse wall of said electrolyzer towards the longitudinal axis thereof and continuing portions running lengthwise of the corresponding longitudinal axis, whereas the left stack of current supply bus at the current inlet into said electrolyzer located at the beginning of each row has a configuration symmetrical with said left stack located at the current outlet from said electrolyzer located at the end of the row.
 2. A system of current-supply buses as claimed in claim 1, wherein said left and said right cathode stacks in each of said electrolyzers located at the end of the row at the current outlet and said left and said right cathode stacks at the current inlet into said electrolyzer located at the beginning of the row, are arranged at the same level. 